Icepack Input Data

Forcing Data

The near surface data required for testing Icepack at a single point have been published on Zenodo and can be found at the path listed for each dataset. Details about each dataset can be found at the link following the Zenodo DOI.

The ASCII files provided contain various atmospheric and/or oceanic forcing fields. Some netCDF files (with metadata) are also available but netCDF is not yet implemented in the Icepack driver. The data files available below are designed only for testing the code, not for use in production runs or as observational data. Please do not publish results based on these data sets. Specific instructions for setting up standard tests (e.g. regression, restart) are in the User's Guide section of the documentation.

A guide to the directory structure of the Icepack input data is also available. Tar files provided below will automatically unpack with this structure.

File Availability:

File name	size	DOI and download link	compatible code versions	date added(+)/ deprecated(-)	file description
All Icepack Forcing Data	0.45 Mb		All		more info

Downloading data from Zenodo

1. Click on the DOI link from the file availability table.

2. Find the file you want to download.

3. Download the file

   3a. Direct download

   Click on either the file name or the "Download" button on zenodo to download the data directly to your machine.

   3b. Download at the command line

   Cut and paste the link to the link address for the file. Then, at the command line on the system to which you want to download the data, use the wget (or curl) command to download. Linux:

   wget $link
   

   macOS:

   curl -O $link
   

4. Optional, but recommended: check the MD5 checksum for the downloaded file against the provided checksum on Zenodo (below the filename).
   Linux:

   md5sum $file
   

   macOS:

   md5 $file
   

Naming standards

For any new files that will be added to the Icepack Input Data files, please note the following:

• File names must be unique from any other files in the archive.
• Existing forcing datasets will be updated only if there are errors found in the existing data.
• New forcing datasets will be added under Icepack_data/forcing/ in a new directory.

Directory structure

An example of how testing data is organized follows. We recommend setting up a similar path structure. You will need to set up your own 'inputdata' path, but the organization of the Icepack_data top level directory should follow the structure below and should automatically unpack as so from the ftp's *.tar.gz files. You will need to extract the data from the downloaded *tar.gz files.

inputdata = '/glade/p/cesm/pcwg_dev/'  
   Icepack_data/
       forcing/
         CFS/
           cfsv2_2015_220_70_01hr.nc
           cfsv2_2015_220_70_01hr.txt
         ISPOL_2004/            
           ISPOL_atm_forcing_05092018.txt
           ISPOL_atm_forcing.txt
           nutrients_daily_ISPOL_WOA_field3.txt
           pop_frc.gx1v3.051202_but_hblt_from_010815_ispol.txt
         NICE_2015/            
           NICE_atm_forcing_05092018.txt
           NICE_atm_forcing.txt
           nutrients_daily_ISPOL_WOA_field3.txt
           oceanmixed_daily_3.txt
        SHEBA
           open_clos_lindsay.dat

Description of Tar file

Icepack requires near surface atmospheric data at a single point. The required fields to force Icepack include: downwelling longwave and shortwave radiative fluxes, latent and sensible heat fluxes, precipitation rate, and near surface potential temperature and specific humidity. Additionally, some forcing data are available for ocean or biogeochemical forcing. Forcing fields that are unavailable in a chosen data file take default values for the season set in namelist.

Further details about the different forcing datasets and how to choose the appropriate forcing can be found in the Icepack Documentation.

CFS:

Hourly atmospheric forcing from the National Centers for Environmental Prediction’s (NCEP) Climate Forecast System, version 2 (CFSv2; Saha and coauthors, 2014) were utilized to generate a one-year time series for Icepack testing. These data were used to create the annual cycle at a point in the Beaufort Sea (70N, 220W) for the period of January 1 00:00UTC - December 31 23:00UTC, 2015. This dataset can be used to run for several years to reach equilibrium of the annual cycle.

Atmospheric forcing fields consist of 2-m air temperature (TEMP2M; K), specific humidity (SPECHUM; kg/kg), 10-m wind velocity in the x and y directions (WNDU10 and WNDV10; m/s), downward solar radiation (DSWSFC; 𝑊/𝑚2), downward longwave radiation (DLWSFC; 𝑊/𝑚2), and precipitation (PRECIP; 𝑘𝑔/𝑚2/𝑠). Icepack’s boundary layer calculation is used to derive sensible and latent heat fluxes.

S. Saha, S. Moorthi, X. Wu, J. Wang, and Coauthors. Two modes of sea-ice gravity drainage: a parameterization for large-scale modeling. J. Climate, 27:2185–2208, 2014. URL: http://dx.doi.org/10.1175/JCLI-D-12-00823.1.

ISPOL 2004:

Atmospheric, oceanic, and biogeochemical forcing are available from the 2004 Ice Station Polarstern (ISPOL) field experiment (Jeffery and Hunke, 2014). The data correspond to the Weddell Sea (67.9S, 54W) from June 16, 2004 to December 31, 2004.

Atmospheric forcing fields consist of 2-m air temperature (K), 2-m specific humidity (kg/kg), 10-m wind velocity in the x and y directions (m/s), downward solar radiation (𝑊/𝑚2), and precipitation (𝑘𝑔/𝑚2/𝑠). These data are available daily, except for incoming atmospheric radiative forcing, which are available 6-hourly. Icepack’s boundary layer calculation is used to derive sensible and latent heat fluxes.

Oceanic forcing fields are derived from a POP 1-degree (gx1v3 simulation). The fields provided are sea surface temperature (K), sea surface salinity (ppt), boundary layer depth (m), ocean velocity in the x and y direction (m/s), and deep ocean heat flux (𝑊/𝑚2). These data are available monthly.

Biogeochemical forcing fields are available from the World Ocean Atlas (NCEP, 2013). The biogeochemical fields provided are nitrate concentration (𝑚𝑚𝑜𝑙/𝑚3) and silicate concentration (𝑚𝑚𝑜𝑙/𝑚3). These data are available daily

N. Jeffery and E.C. Hunke. Modeling the winter-spring transition of first-year ice in the western Weddell Sea. J. Geophys. Res. Oceans, 119:5891–5920, 2014. URL: http://dx.doi.org/10.1002/2013JC009634

National Centers for Environmental Information. World Ocean Atlas Version 2. Natl. Ocn. and Atm. Admin, 2013. URL: https://www.nodc.noaa.gov/OC5/woa13/.

NICE 2015:

Atmospheric, oceanic, and biogeochemical forcing are available from the 2015 Norwegian Young Sea Ice Cruise (N-ICE) field experiment (Duarte and co-authors, 2017). The data correspond to the Weddell Sea (67.9S, 54W) from June 16, 2004 to December 31, 2004. The data correspond to the Arctic Ocean north of Svalbard along the N-ICE drift track (83N, 16E to 80N, 5E) from April 24, 2015 to June 6, 2015.

Atmospheric forcing fields consist of 2-m air temperature (K), 2-m specific humidity (kg/kg), 10-m wind velocity in the x and y directions (m/s), downward solar radiation (𝑊/𝑚2), and precipitation (𝑘𝑔/𝑚2/𝑠). Icepack’s boundary layer calculation is used to derive sensible and latent heat fluxes. These data are available daily, except for incoming atmospheric radiative forcing, which are available 6-hourly.

Oceanic forcing fields are available from a Parallel Ocean Program (POP) 1-degree (gx1v3) simulation. These fields consist of sea surface temperature (K), sea surface salinity (ppt), boundary layer depth (m), ocean velocity in the x and y direction (m/s), and deep ocean heat flux (𝑊/𝑚2). These data are available daily.

Biogeochemical forcing fields are available from the World Ocean Atlas (NCEP, 2013). The biogeochemical fields provided are nitrate concentration (𝑚𝑚𝑜𝑙/𝑚3) and silicate concentration (𝑚𝑚𝑜𝑙/𝑚3).

P. Duarte and Coauthors. Sea ice thermohaline dynamics and biogeochemistry in the Arctic Ocean: Empirical and model results. J. Geophys. Res. Biogeo., 122:1632–1654, 2017. URL: http://dx.doi.org/10.1002/2016JG003660.

National Centers for Environmental Information. World Ocean Atlas Version 2. Natl. Ocn. and Atm. Admin, 2013. URL: https://www.nodc.noaa.gov/OC5/woa13/.

SHEBA:

The ice opening and closing rates (1/s) are derived from the Surface HEat Budget of the Arctic field experiment. These data and have been used previously in Cecilia Bitz’s column model. For additional information see the following websites:

https://atmos.washington.edu/~bitz/column_model/

https://atmos.washington.edu/~bitz/column_model/notes_forcing_data

Climatological

Monthly climatological atmospheric forcing are available, but are not a required file to download. These data are based on (Lindsay, 1998) and have default values representative of winter, spring and summer.

Lindsay, R.W. (1998). Temporal Variability of the Energy Balance of Thick Arctic Pack Ice. Journal of Climate. https://doi.org/10.1175/1520-0442(1998)011<0313:TVOTEB>2.0.CO;2